Production of magnetic steels with a high content of silicon



Patented Sept. 15, 1925.

FELIX THUAUD,

or rams, FRANCE, ASSIGNOR or own-HALF '10 socrn'rn ELECTRO- METALLURGIQUES DE MONTRICHEB, OF PARIS, FRANCE, A CORPORATION OF rumor.

rnonuc'rron or MAGNETIC STEELS WITH A HIGH con'rmr'r or SIIQICOIN.

No Drawing.

To all whom it may concern:

Be it known that I, FEL X THUAUD, a French citizen, and resident of 16 rue Jean Jacques Rousseau, "Paris, France, hate invented certain new and useful Improvementsin the Production of Magnetic Steels with a High Content of Silicon, of which the following is a specification.

The present invention relates to improvements in the process for the manufacture of magnetic steels having a high content of silicon, these improvements being for the purpose of improving the qualities of the products obtained.

Magnetic steels are manufactured either in a converter, or in a Martin furnace (for inferior qualities), .or, more frequently. in electric furnaces (for superior qualities).

, The general formula used is as follows:

Per cent.

Carbon 0.10 to 0.20

Numerous experiments have shown that the formulae or compositions approaching this do not reduce the hysteresis losses sufliciently to enable a complete or almost complete demagnetization of metalexposed to the action of a magnetic field. In fact the hysteresis meter indicates losses of the order of from 2 to 3 watts due to.a considerable tension which becomes noticeable in the form of heat.

For reducing these losses of energy and to reduce them to a theoretical minimum there is used, according to the present invention, the following composition for steels 'under consideration.

' Per cent. Carbon 0.02 to 0.05 Manganese 0.04 to 0.07 Silicon 3.50 to 4.20 Nickel 0.05 to 3 Titanium 0.05 to 1 The metal is prepared in an electric furnace after repeated refining and when it forms pure iron, that is to say, a product Application flled August 4, 1924. Serial No. 730,086

corresponding to the following chemical composition 7 Carbon 0.02% Manganese traces. Silicon traces. Sulphur traces. Phosphorus traces.

there are incorporated therewith: 1 1. Silicon.

' 2. Nickel.

3. Titanium.

Nickel and titanium have never before been used in the manufacture of magnetic sheets. The application of these metals in the above manufacture constitutes one of the characteristics of the invention. It has for its object to determine an appreciable improvement of the quality of the products obtained: the hysteresis is reduced and decreased from a value of 31V to a value below 1.2 W. and the permeability is increased by about 40%. After rolling, the metal, instead of being simply annealed in closed vessels, according to the usual method, is subjected to a thermal treatment in a closed vessel, but in the presence of finely powdered oxide. of magnetic'iron. This treatment constitutes a decarbonization by cementation which has hitherto not been applied for annealing magnetic sheets. The treatment in question is for the purpose not only of imparting to the final product the maximum possible ductility but also to reducethe content of carbon to its initial value, this content having been modified appreciably during the course of treatment by reason of repeated contacts of the metal with the fuel used.

Having thus described my invention what I declare as new and deslre to secure by Letters Patent is 1. A process for the manufacture of high silicon. magnetic steels, comprising, alloying nickel and titanium with an alloy of iron and silicon, and then annealing the resulting product in a closed vessel and 1n the presence of finely divided magnetic iron oxide.

2. A process for the manufacture of high silicon magnetic steels, comprising, repeat- 1 edlyrefining steel until it is substantially pure iron, alloying silicon, nickel and titanium therewith, rolling the resulting metal, and then annealing the rolled product in a closed vessel and in the presence of finely divided magnetic iron oxide.

3. A process for the production of high silicon magnetic steel, comprising, refining steel until it is substantially pure ron and contains only about 0.2% of carbon and only traces of manganeze, silicon, sulphur, and phosphorus, alloying the product thus obtained, with operative amounts of slicon, nickel, and titanium, so that the final product contains carbon not exceeding 0.05%,

manganese not exceeding 0.07%, silicon not exceeding 4.20%, nickel not exceeding 3% and titanium not exceeding 1%, rolling the resultant product into metal plate, and then heating such metal plate in a closed vessel and in the presence of finely powdered magnetic iron .oxide.

FELIX THUAUD; 

